Group vi metal deposition process

ABSTRACT

Provided is a process for the vapor deposition of molybdenum or tungsten, and the use of molybdenum hexacarbonyl (Mo(CO) 6 ) or tungsten hexacarbonyl (W(CO) 6 ) for such deposition, e.g., in the manufacture of semiconductor devices in which molybdenum-containing or tungsten-containing films are desired. In accordance with one aspect of the invention, molybdenum hexacarbonyl (Mo(CO) 6 ) has been found in vapor deposition processes such as chemical vapor deposition (CVD) to provide low resistivity, high deposition rate films in conjunction with a pulsed deposition process in which a step involving a brief pulse of H 2 O is utilized. This pulsing with H 2 O vapor was found to be effective in reducing the carbon content of films produced from Mo(CO) 6 -based CVD processes.

FIELD OF THE INVENTION

This invention belongs to the field of thermal deposition of certainGroup VI metal precursors to form, for example, molybdenum and tungstenmetal onto microelectronic substrates.

BACKGROUND OF THE INVENTION

In consequence of its characteristics of extremely high melting point,low coefficient of thermal expansion, low resistivity, and high thermalconductivity, molybdenum is increasingly utilized in the manufacture ofsemiconductor devices, including use in diffusion barriers, electrodes,photomasks, power electronics substrates, low-resistivity gates, andinterconnects.

Such utility has motivated efforts to achieve deposition of molybdenumfilms for such applications that is characterized by high conformalityof the deposited film and high deposition rate to accommodate efficienthigh-volume manufacturing operations. This in turn has informed effortsto develop improved molybdenum source reagents useful in vapordeposition operations, as well as improved process parameters utilizingsuch reagents.

SUMMARY OF THE INVENTION

The present invention relates to vapor deposition of certain Group VImetals, such as tungsten and molybdenum, and the use of molybdenumhexacarbonyl (Mo(CO)₆) and tungsten carbonyl (W(CO)₆) for suchdeposition, e.g., in the manufacture of semiconductor devices in whichmolybdenum or tungsten films are desired. In one aspect of the presentinvention, molybdenum hexacarbonyl (Mo(CO)₆) has been found in vapordeposition processes such as chemical vapor deposition (CVD) to providelow resistivity, high deposition rate films in conjunction with a pulseddeposition process in which a step involving a brief pulse of H₂O isutilized. In this regard, we have found this intermediate step ofpulsing with H₂O vapor to be effective in reducing the carbon content offilms produced from Mo(CO)₆-based CVD processes. In one aspect, theinvention relates to a process for forming a molybdenum-containingmaterial on a substrate, comprising sequentially contacting thesubstrate with molybdenum hexacarbonyl vapor, H₂O vapor, and a reducinggas, under vapor deposition conditions, to deposit themolybdenum-containing material on the substrate. The pulsing sequence isrepeated until a desired film thickness has been achieved on thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the X-ray diffraction pattern (XRD) of a molybdenum filmutilizing the process of the invention, conducted at a stage temperatureof 400° C. with H₂ co-reactant and H₂O pulses as set forth in Example 1.No Mo₂C was detected.

FIG. 2 is a Secondary Ion Mass Spectrum (SIMS) of the film prepared inExample 1, i.e., the 400° C. deposited Mo film. The carbon and oxygenimpurity levels were 1.1 and 0.24 atomic %, respectively. An annealedresistivity of 12.4 μΩ·cm was the lowest value achieved from Mo(CO)₆.The carbon, nitrogen, and oxygen concentrations in atoms per cc aredepicted on the vertical axis on the left and the molybdenum, silicon,and titanium intensity is depicted in arbitrary units is depicted on theright vertical axis.

FIG. 3 illustrates the effect of shorter pulse intervals for Mo(CO)₆ andH₂O in yielding films with lower resistivity. A 0.25 second pulse ofMo(CO)₆ followed by 100 seconds of H₂ at a flow rate of 1200 sccm (dots)achieved as an as-deposited resistivity of about 30 μΩ-cm. Additions of1 second pulse of H₂O vapor followed the Mo(CO)₆ pulse (squares) reducethe as-deposited resistivity to about 20 μΩ-cm.

FIG. 4 compares resistivity of the resulting Mo film using pulse timesof 1 second and 3 seconds of H₂O and shows that increasing pulseinterval does not improve resistivity.

FIG. 5 illustrates the effect of 400° C. vs 500° C. depositiontemperature on as-deposited resistivity.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to vapor deposition of certain Group VImetal-containing compounds, such as molybdenum and tungsten, and the useof molybdenum hexacarbonyl (Mo(CO)₆) and tungsten carbonyl (W(CO)₆) forsuch deposition, e.g., in the manufacture of microelectronic devices inwhich molybdenum or tungsten films are desired. In one aspect of thepresent invention, molybdenum hexacarbonyl (Mo(CO)₆) has been found invapor deposition processes such as chemical vapor deposition (CVD) toprovide low resistivity, high deposition rate films. In one aspect, theinvention relates to a process for forming a molybdenum-containingmaterial on a substrate, comprising contacting the substrate withmolybdenum hexacarbonyl (Mo(CO)₆) vapor under vapor depositionconditions, to deposit the molybdenum-containing material on thesubstrate. It has been found that in various embodiments of theinvention, the use of molybdenum hexacarbonyl (Mo(CO)₆) as a precursorfor vapor deposition of molybdenum-containing material on substrates,followed by a pulse step of an oxidizing gas, such as H₂O vapor,followed by a reducing gas, for example H₂, can provide a molybdenumfilm with as-deposited resistivity of less than 25 μΩ-cm. Further, thefilms of the invention have a reduced carbon content versus whattypically results from the use of Mo(CO)₆ as precursor, in general, lessthan 5%, or less than 2, or less than 1.2% (atomic percentage) carbon.Thus, in a first aspect, the invention provides a process for forming amolybdenum-containing material or a tungsten-containing material on asubstrate, comprising contacting the substrate with Mo(CO)₆ or W(CO)₆,respectively, under pulsed vapor deposition conditions, wherein thepulsed vapor deposition conditions comprise:

(i) exposure of the substrate to Mo(CO)₆ or W(CO)₆;

(ii) exposure of the substrate to an oxidizing gas; and

(iii) exposure of the substrate to a reducing gas.

In certain embodiments, (i), (ii), and (iii) are steps conductedsequentially. In other embodiments, (i), (ii), and (iii) are repeateduntil a desired thickness of a molybdenum or tungsten containing filmhas been deposited on the substrate.

In certain embodiments of the present invention, the oxidizing gas iscomprised of gases chosen from H₂O vapor, H₂O₂, O₃, and N₂O. In certainembodiments of the present invention, the reducing gas is comprised ofgases chosen from H₂, hydrazine (N₂H₄), methyl hydrazine, t-butylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and NH₃. Itwill be appreciated that given the oxidative potentials of H₂O₂ and O₃,such gasses should not be utilized in conjunction with hydrazine (N₂H₄), methyl hydrazine, t-butyl hydrazine, 1,1-dimethylhydrazine, or1,2-dimethylhydrazine, or if utilized sequentially, any such gasesremaining from such a step should be purged from the reactor beforeexposure of the substrate to the other reactant.

In certain embodiments, (i) is followed by a combination of (ii) and(iii), with the proviso that the reducing gas is utilized in a molarexcess relative to the oxidizing gas, and further with the proviso thatwhen the reducing gas is hydrazine, methyl hydrazine, t-butyl hydrazine,1,1-dimethylhydrazine, or 1,2-dimethylhydrazine the oxidizing gas isother than H₂O₂ and O₃.

The Mo(CO)₆ or W(CO)₆ may be deposited at a pressure in the range offrom about 0.1 to 50 Ton, or in the range of from 0.5 Ton to 25 Ton, orin the range of from 1 to 5 Torr.

In one embodiment, a three step pulse sequence is generally comprised ofMo(CO)₆ (or W(CO)₆) vapor, followed by H₂O, followed by a reducing gassuch as H₂, hydrazine, methyl hydrazine, t-butyl hydrazine,1,1-dimethylhydrazine, or 1,2-dimethylhydrazine, followed by Mo(CO)₆vapor, etc., until a desired thickness of Mo (or W) film has beenobtained. In certain embodiments, the pulse duration of Mo(CO)₆ or W(CO)vapor is from about 100 micro seconds to about 1 second, or about 500microseconds to about 0.5 seconds, or from about 0.15 to about 0.35seconds, or about 0.25 seconds. In certain embodiments, the pulseduration of the oxidizing gas exposure (e.g., H₂O vapor) is about 0.5 toabout 3 seconds, or about 0.8 seconds to about 1.2 seconds, or about 1second. In certain embodiments, the pulse duration of the reducing gasexposure is about 50 seconds to about 200 seconds, or about 75 secondsto about 125 seconds, or about 100 seconds.

In various embodiments, the vapor deposition conditions comprise aninert atmosphere, save for the steps involving oxidizing gas and areducing gas.

The vapor deposition conditions may be of any suitable type, and may forexample comprise a reducing ambient (vapor) such as hydrogen, hydrazine,methyl hydrazine, t-butyl hydrazine, 1,1-dimethylhydrazine, or1,2-dimethylhydrazine, so that the molybdenum-containing (ortungsten-containing) material comprises elemental molybdenum (ortungsten) material in the deposited film. The molybdenum-containing (ortungsten-containing) material so deposited may comprise, oralternatively consist, or consist essentially of, elemental molybdenum,or molybdenum oxide, or other molybdenum-containing material ortungsten, tungsten oxide, or other tungsten-containing material.

In one embodiment, the molybdenum or tungsten-containing layer depositedon the substrate surface may for example be formed by pulsed chemicalvapor deposition (CVD) or atomic layer deposition (ALD) or other vapordeposition technique, without the prior formation of a nucleation layerand thus directly with molybdenum hexacarbonyl (Mo(CO)₆) vapor ortungsten hexacarbonyl (W(CO)₆) vapor. The respective molybdenum ortungsten hexacarbonyl (Mo(CO)₆)vapor contacting steps, oxidizing gas(e.g., H₂O vapor), and reducing gas steps may be carried outrepetitively for as many cycles as are desired to form the desiredthickness of the molybdenum film.

As used herein, the term “microelectronic device” corresponds tosemiconductor substrates, including 3D NAND structures, flat paneldisplays, and microelectromechanical systems (MEMS), manufactured foruse in microelectronic, integrated circuit, or computer chipapplications. It is to be understood that the term “microelectronicdevice” is not meant to be limiting in any way and includes anysubstrate that includes a negative channel metal oxide semiconductor(nMOS) and/or a positive channel metal oxide semiconductor (pMOS)transistor and will eventually become a microelectronic device ormicroelectronic assembly. The semiconductor device may be of anysuitable type, and may for example comprise a DRAM device, 3-D NANDdevice, or other device or device integrated structure. In variousembodiments, the substrate may comprise a via in which themolybdenum-containing material is deposited. The device may, forexample, have an aspect ratio of depth to lateral dimension that is in arange of from 10:1 to 40:1. In still other embodiments, the device maybe a film used in a flat-panel display or mobile device.

The substrates located on such microelectronic devices utilized in thedeposition process of the invention may be of any suitable type, and mayfor example comprise a semiconductor device substrate, e.g., a siliconsubstrate, a silicon dioxide substrate, or other silicon-basedsubstrate. In various embodiments, the substrate may comprise one ormore metallic or dielectric substrates, for example, Co, Cu, Al, W, WN,WC, TiN, Mo, MoC, SiO₂, W, SiN, WCN, Al₂O₃, AlN, ZrO₂, HfO₂, SiO₂,lanthanum oxide (La₂O₃), tantalum nitride (TaN), ruthenium oxide (RuO₂),iridium oxide (IrO₂), niobium oxide (Nb₂O₃), and yttrium oxide (Y₂O₃).

In certain embodiments, for example in the case of an oxide substratesuch as silicon dioxide, or alternatively a silicon or polysiliconsubstrate, the substrate may be processed or fabricated to include abarrier layer thereon, e.g., titanium nitride, for subsequentlydeposited material.

In a further aspect, the invention provides a process for forming amolybdenum-containing material on a substrate, wherein the substrate ischosen from titanium nitride, tantalum nitride, aluminum nitride,aluminum oxide, zirconium oxide, hafnium oxide, silicon dioxide, siliconnitride, lanthanum oxide, ruthenium oxide, iridium oxide, niobium oxide,and yttrium oxide, comprising contacting the substrate with Mo(CO)₆,under pulsed vapor deposition conditions, wherein the pulsed vapordeposition conditions comprise:

(i) exposure of the substrate to Mo(CO)₆ for a period of about 100microseconds to about one second;

(ii) exposure of the substrate to H₂O vapor for a period of about 0.8 toabout 1.2 seconds; and

(iiI) exposure of the substrate to hydrogen gas for a period of about 75seconds to about 125 seconds.

In certain embodiments, (i), (ii), and (iii) are steps conductedsequentially. In other embodiments, (i), (ii), and (iii) are repeateduntil a desired thickness of a molybdenum-containing material has beendeposited on the substrate.

The molybdenum or tungsten-containing material deposited in accordancewith the method of the present invention may be characterized by anyappropriate evaluation metrics and parameters, such as deposition rateof the molybdenum-containing material, the carbon content of themolybdenum-containing material, film resistivity of the depositedmolybdenum-containing material, film morphology of the depositedmolybdenum or tungsten-containing material, film stress of the depositedmolybdenum or tungsten-containing material, step coverage of thematerial, and the process window or process envelope of appropriateprocess conditions. Any appropriate evaluation metrics and parametersmay be employed, to characterize the deposited material and correlatesame to specific process conditions, to enable mass production ofcorresponding semiconductor products. Advantageously, the process of theinvention is capable of depositing a film of high purity molybdenum ortungsten onto a microelectronic device. In the case of molybdenum, thefilms were found to have a number of desirable qualities. Accordingly,in a further aspect, the invention provides a microelectronic devicehaving a molybdenum film deposited thereon, wherein said film comprisesgreater than 95% molybdenum, less than 1% oxygen, less than 4% ofcarbon, and a resistivity of less than 25 μΩ·CM when measured on a filmhaving a thickness of 200 Å.

This invention can be further illustrated by the following examples ofcertain embodiments thereof, although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

EXAMPLES

General Procedure:

A semiconductor device may be fabricated by the following sequence ofprocess steps on the substrate comprising a titanium nitride barrierlayer on the silicon dioxide base layer.

Step 1: Purging the deposition chamber;

Step 2: contacting the barrier layer (TiN layer) of the substrate with apulse of molybdenum hexacarbonyl (Mo(CO)₆), followed by a pulse of H₂Ovapor, followed by hydrogen (H₂), for example at temperature on theorder of 400° C.;

Step 3; The system is purged under H₂ or inert gas (e.g., Ar) to allowfor complete reaction of the molybdenum hexacarbonyl (Mo(CO)₆)with theH₂ co-reactant and substrate.

Step 4: repeating Steps 1-3 as necessary to form a molybdenum film layerof desired characteristics.

Example 1

As 800° C. As- deposited 800° C. RTH CVD XRF Mo deposited XRF C AnnealedXRF C Temp thickness Resistivity (μg/cm²/ Resistivity (μΩ · cm/ (° C.)(Å) (μΩ-cm) 10 nm Mo) (μΩ · cm) 10 nm Mo) Example A 500 170.8 22.7 0.2714.0 0.21 Example B 400 198.0 23.7 0.29 12.4 0.15

Example 2

Step 1: Purging the deposition chamber;

Step 2: Contacting the barrier layer (TiN layer) of the substrate with apulse of molybdenum hexacarbonyl (Mo(CO)₆), followed by hydrogen (H₂),for example at temperature on the order of 500° C.;

Step 3; The system is purged under H₂ or inert gas (e.g., Ar) to allowfor complete reaction of the molybdenum hexacarbonyl (Mo(CO)₆)with theH₂ co-reactant and substrate.

Step 4: repeating Steps 1-3 as necessary to form a molybdenum film layerof desired characteristics.

CVD As-deposited Temperature XRF Mo Resistivity Co-reactant (° C.) (nm)(μΩ · cm) Without H₂O pulse 500 18.7 32.9 With H₂O pulse 500 18.3 20.3

1. A process for forming a molybdenum-containing material or atungsten-containing material on a substrate, comprising contacting thesubstrate with Mo(CO)₆ or W(CO)₆, respectively, under pulsed vapordeposition conditions, wherein the pulsed vapor deposition conditionscomprise: (i) exposure of the substrate to Mo(CO)₆ or W(CO)₆; (ii)exposure of the substrate to an oxidizing gas; and (iii) exposure of thesubstrate to a reducing gas.
 2. The process of claim 1, wherein thesubstrate is chosen from titanium nitride, tantalum nitride, aluminumnitride, aluminum oxide, zirconium oxide, hafnium oxide, silicondioxide, silicon nitride, lanthanum oxide, ruthenium oxide, iridiumoxide, niobium oxide, and yttrium oxide.
 3. The process of claim 1,wherein the exposure of the substrate to Mo(CO)₆ is conducted at atemperature of from about 250° to about 750° C.
 4. The process of claim1, wherein the exposure of the substrate to W(CO)₆ is conducted at atemperature of from about 250° to about 750° C.
 5. The process of claim1, wherein the oxidizing gas is comprised of gases chosen from H₂Ovapor, H₂O₂, O₃, and N₂O.
 6. The process of claim 1, wherein thereducing gas is comprised of gases chosen from H2, hydrazine , methylhydrazine, t-butyl hydrazine, 1,1-dimethylhydrazine,1,2-dimethylhydrazine, and NH₃.
 7. The process of claim 1, wherein thereducing gas is H₂ and the temperature is about 300 to about 600° C. 8.The process of claim 1, wherein the reducing gas comprises H₂.
 9. Theprocess of claim 1, wherein the oxidizing gas comprises H₂O vapor. 10.The process of claim 1, wherein the duration of (i) is about 100 microseconds to about 1 second.
 11. The process of claim 1, wherein theduration of (i) is about 0.15 to about 0.35 seconds.
 12. The process ofclaim 1, wherein the duration of (ii) is about 0.5 to about 3 seconds.13. The process of claim 1, wherein the duration of (ii) is about 0.8 toabout 1.2 seconds.
 14. The process of claim 1, wherein the duration of(iii) is about 50 to about 200 seconds.
 15. A process for forming amolybdenum-containing material on a substrate, wherein the substrate ischosen from titanium nitride, tantalum nitride, aluminum nitride,aluminum oxide, zirconium oxide, hafnium oxide, silicon dioxide, siliconnitride, lanthanum oxide, ruthenium oxide, iridium oxide, niobium oxide,and yttrium oxide, comprising contacting the substrate with Mo(CO)₆,under pulsed vapor deposition conditions, wherein the pulsed vapordeposition conditions comprise: (i) exposure of the substrate to Mo(CO)₆for a period of about 100 microseconds to about one second; (ii)exposure of the substrate to H₂O vapor for a period of about 0.8 toabout 1.2 seconds; and (iii) exposure of the substrate to hydrogen gasfor a period of about 75 seconds to about 125 seconds.
 16. The processof claim 15, wherein (i), (ii), and (iii) are steps conductedsequentially.
 17. The process of claim 15, wherein (i), (ii), and (iii)are repeated until a desired thickness of a molybdenum-containingmaterial has been deposited on the substrate.
 18. A microelectronicdevice having a molybdenum film deposited thereon, wherein said filmcomprises greater than 95% molybdenum, less than 1% oxygen, less than 4%of carbon, and a resistivity of less than 25 μΩ·CM when measured on afilm having a thickness of 200 Å.
 19. The device of claim 18, whereinsaid device is chosen from a DRAM device, a 3D-NAND device, or a Logicdevice.